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Intolerance to carbohydrates
Last reviewed: 19.11.2021
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Carbohydrate intolerance (intolerance of carbohydrates) is the inability to digest certain carbohydrates because of the lack of one or more intestinal enzymes. Symptoms of carbohydrate intolerance include diarrhea, bloating and flatulence. The diagnosis is based on clinical signs and a respiratory test with H2. Treatment of carbohydrate intolerance consists in the elimination of disaccharides from food.
Read also: What if the baby does not tolerate lactose?
[What causes carbohydrate intolerance?
Deficiency of enzymes can be congenital, acquired (primary) or secondary. Congenital deficiency is rare.
Acquired lactase deficiency (primary adult hypolactasia) is the most common form of carbohydrate intolerance. High levels of lactase are observed in newborns because of the need to digest milk; in most ethnic groups (80% of blacks and Hispanics, almost 100% of Asians), lactase levels decrease after a period of breastfeeding, which prevents older children and adults from digesting significant amounts of lactose. At the same time, 80-85% of the inhabitants of northwestern Europe have a good lactase production throughout their lives, which allows them to digest milk and dairy products. It remains unclear why more than 75% of the world's population has a deficiency of this enzyme.
Secondary lactase deficiency is associated with the conditions under which damage to the mucous membrane of the small intestine (eg, celiac disease, tropical sprue, acute intestinal infections). In infants, a temporary secondary deficit of disaccharidase may complicate the course of intestinal infections or surgical interventions on the abdominal cavity. The exit from the disease is accompanied by an increase in the activity of the enzyme.
What happens when carbohydrates are intolerant?
Disaccharides are normally cleaved to monosaccharides from disaccharides [eg, lactase, maltase, isomaltase, sucrose (invertase)], localized on the brush border of the enterocytes of the small intestine. Undigested disaccharides cause an increase in osmotic pressure, which attracts water and electrolytes into the lumen of the intestine, causing watery diarrhea. Bacterial fermentation of carbohydrates in the large intestine causes gas formation (hydrogen, carbon dioxide and methane), leading to marked swelling, flatulence and abdominal pain.
Symptoms of Carbohydrate Intolerance
Symptoms of carbohydrate intolerance are similar for all conditions of disaccharidase deficiency. A child with lactose intolerance develops diarrhea after receiving a significant amount of milk and there may be no gain in weight. In adults, watery diarrhea, bloating, excessive gas leakage, nausea, rumbling in the abdomen and intestinal cramps after taking lactose can be observed. Patients notice this early enough and avoid eating dairy products. Symptoms of carbohydrate intolerance usually appear after eating an equivalent of 8-12 ounces [1 ounce (amer.) = 29.56 ml] of milk. Diarrhea can be quite severe, causing the removal of other nutrients before they are absorbed. Symptoms may be similar to irritable bowel syndrome, which requires differential diagnosis.
Where does it hurt?
What's bothering you?
Diagnosis of carbohydrate intolerance
Lactose intolerance is usually diagnosed by careful collection of anamnesis, confirmed by diet. Usually patients have a history of intolerance to milk and dairy products. The diagnosis can be assumed if the stool in the form of chronic or intermittent diarrhea has an acidic environment (pH <6) and can be confirmed by a respiratory test with H2 or by a study for tolerance to lactose.
In a respiratory test with H2, the patient takes 50 g of lactose and H2, which is formed by metabolism of undigested lactose under the action of microflora, and is measured by the device during breathing at 2, 3 and 4 hours after ingestion. In patients with significant manifestations of the disease, the increase in H2 reaches more than 20 mmol above the baseline value. The sensitivity and specificity of the study is more than 95%.
The test for tolerance to lactose is less specific. Lactose is taken orally (1.0-1.5 g / kg body weight). Blood glucose is measured before meals and 60 and 120 minutes after. Patients with intolerant lactose develop diarrhea, bloating and a feeling of discomfort for 20-30 minutes and blood glucose levels do not rise above 20 mg / dL (<1.1 mmol / L) of baseline. The low activity of lactase in the jejunal biopsy confirms the diagnosis, but in this case endoscopy is not an easy study to obtain a tissue sample.
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Treatment of carbohydrate intolerance
Carbohydrate intolerance is easily controlled, excluding sugar from the food that can not be absorbed in the intestine (eg, a lactose-free diet in case of lactase deficiency). But, since the degree of malabsorption of lactose varies greatly, many patients can take up to 12 ounces (18 grams) of milk lactose daily without developing symptoms. Usually yogurts are allowed for food, since they contain a noticeable amount of lactase formed by Lactobacilli contained in it.
For patients who want to consume milk, a method has been developed for pretreating lactose by adding lactase to the milk, which allowed such patients to consume milk. Adding an enzyme should only be a supplement, but not a use instead of a restrictive diet. Patients with intolerant lactose should additionally take calcium supplements (1200-1500 mg / day).